Pile fabrics



T. A. FEILD, JR.. ETAL Feb. 14, 1961 2,971,245

PILE FABRICS Filed Aug. 20, 1956 2 SheetsSheet 1 mvavrons THEOPHILUS A FEILD ,JR. CHARLES W. DAVISSON Arrgmvzr Feb. 14, 1961 T A. FEILD, JR., ETAL FILE FABRICS Filed Aug. 20, 1956 2 Sheets-Sheet 2 INVENTORS THEOPHILUS A.FEILD,J R. CHARLES W. DAVISSON BY GMQ /ZEZ A TTORNEV t I l United States Charleston, W. Va., assignors to Union Carbide orporation, a corporation of New York Filed Aug. 20, 1956, ser. No. 695,224

17 Claims. (Cl. 23-78) This invention relates to pile fabrics made from acrylonitrile-containing polymers. More particularly, this invention relates to pile fabrics in which the pile structure contains fibers of acrylonitrile-containing polymers, which fabrics have improved soil hiding power, freedom from fibrillation, and excellent wear resistance. Even more particularly, this invention is directed to a pile fabric having a pile structure comprised of a substantially unoriented nodular surfaced polymeric fiber as a novel article of manufacture.

Acrylonitrile-co ntaining polymers have been known to yield fibers of good mechanical properties for many textile uses, such as in knitted, woven, and pile fabrics. Pile fabrics in general may be regarded as being made up of two functional components: the woven or knitted structure that provides the mechanical and dimensional integrity of the fabric, and the pile structure that carries the abrasive load and is responsible for the general appearance of the fabric, and that consequently shows the effects of dirt and of abrasive wear.

Pile fabrics such as simulated furs, fleeces, velvets, and carpeting have been made using such synthetic fibers in the pile structure, providing many new and novel prod% ucts. It is recognized that while such synthetic fibers achieve many desirable effects, they also possess undesirable effects in certain applications. In pile carpeting for example, most of the acrylonitrile polymeric fibers atent "ice and channels. Theselatter features are recognized as being necessary to have low soiling fiber. Certain mechanical properties of the fiber also are necessary to produce the resilience and abrasion resistance necessary for acceptablecarpets from synthetic fibers. According to R. Hill in his book Fibers from Synthetic Polymers the fibers must be characterized by great flexibility and lack of brittleness combined with adequate tensile strength, and substantial stretching and drawing-out of the fibers will give them the special properties which are essential. In most cases, it is this stretching and orientation which imparts the desirable strength and lack of brittlenes and results in the formation of useful fibers.

In wearing quality, carpeting having a pile structure of acrylonitrile polymeric fibers possessing such proper ties has-left much to be desired. The surface of such carpets after wear has a tendency to fuzz-up and individual fibers will entangle into small balls. Such effects have been referred to as fuzzing and pilling. Sprouting, i.e., an entire tuft coming out of the carpet, is also quite likely to occur in pile fabrics made from these synthetic fibers. It is recognized that with some fibers crimping of the fibers is necessary to reduce pilling, fuzzing, and sprouting after wear. Crimping, by itself, has not been the answer to a long wearing synthetic fiber carpeting. Such other effects as tufting, i.e. when individual fibers group together to give a lean, grainy appearance to the carpet, and matting of tufts also occasionally arise with synthetic fibers. The crush resistance, that is, the resistance to loss of thickness of the pile due to wear, is also a very important characteristic desired in synthetic fiber pile carpeting. While there are well known and have a tendency to soil easily. Efforts toward'the irnprovement of soil resistanceof pile carpeting have been primarily directed to the application of so called clean soils, such as colloidal silica and alumina, to the carpeting. Such treatments have not been altogether satisfactory because theyresulted in too little improvementin apparent soiling resistance and in a type of improvement which is not durable and. requires frequent reapplication of the treatment. In addition, such methods have resulted in a dusty and whitened-appearance with loss of apparent luster of the carpet.

It is recognized in the carpet industry that soiling is critically related to the soil-hiding or soil-obscuring property of the fiber and not alone on the soil retention of the fibers. For instance, wool has a fairly high degree of soil 9 retention and also a high degree of soil-hiding power and thus appears cleaner than a fabric containing an equivafibers possess the properties believed. necessary to give a low soiling carpeting. i

It is recognized in the art, from studies made. on pile carpeting, that. pile fibers f must have good resilience, good abrasion resistance, a smooth surface, andcircular cross-section with adiar'neterpf at least 27 microns, the

surface being essentially free from indentations, asperities,

reliable methods for testing strength, elongation, and tendency to fibrillation of fibers, the resultant effect of various forces to which a carpet is subjected makes results of accelerated wear testing machines inconclusive. Tests under conditions of actual use are thus preferred by most carpet manufacturers. The test generally is conducted by observing the behavior of pilecarpets laid in heavily traveled corridors to detect these undesirable properties.

Another tendency of these acrylic fibers which has created difficulty in carpeting is that of fibrillating, or the tendency of the pile fibers to split on. the ends which will tend to hold and lock-in dirt particles and which are difficult to remove by ordinary cleaning methods.

This condition is quite undesirable and makes the fabric appear soiled with only slight use and slight retention of dirt. Presumably the fibrillation of fiber also assists in the tufting and matting effect. A

It is therefore an object of the present invention to provide an improved pile fabric from 'acrylonitrile polymers which will have increased soil-hiding power and apparent soiling'resistance.

, it is another object of the present invention to provide a pile fabric having good wearing qualities without fuzzing, pilling, sprouting, and crushing in which the pile structure of the fabric contains an acrylonitrile polymeric fiber.

According to the present invention, we have now discovered that the above objects can be achieved by employing a substantially unoriented acrylonitrile polymeric fiber in the pile structure of pile fabrics. The fibers to. be employed in the practice of this invention are characterized by having a high degree of opacity and a surface substantially covered with minute nodes, ranging in size between about 2 microns and 30 microns. This discovery is particularly surprising in that the fibers herein employed possess properties which are contrary to all expectations of the properties believed necessary for a good pile fiber. Instead of these fibers being penalized by their mechanical shortcomings, we have found they can provide such un- I the temperature.

. 3 expected advantages in pile fabrics as good wearing qualities, improved soil hiding power, and a freedom from fibrillation under severe abrasion. Thus instead of using a round, smooth, substantially uncrenulated surface on a high tenacity, oriented fiber as formerly believed necessary for quality pile fabrics, we have found that a rough, nodular surfaced, low tenacity, substantially unoriented fiber will produce these unexpected results.

A fuller understanding of the invention may be facilitated by reference to the accompanying drawings wherein:

Fig. v1 is a negative photomicrograph of a nodular surfaced fiber of this invention, taken at 500 X magnifica tion,

Fig. 2 is a positive photograph taken of a section of a pile fabric prepared from nodular surfaced fibers. in accordance with this invention,

The fibers to be employed in the pile structure of the fabrics when employed as the pile component in pile fabrics is directly attributable to the optical geometry of the fiber surface and to the degree of opacity of the fiber. To illustrate what is meant, and as a means for drawing a comparison only, the appearance of a black object as viewed by direct light on a flat surface will show a true black color because it absorbs all the light and reilects none back to the viewer. On the other hand, if the same black object is viewed on an opaque, irregular surface with the irregularities approaching the size of the black object, the object appears light gray in color, due to the reflection to the viewer of part of the light from the irregirnproved pile fabrics of this invention can be produced from acrylonitrile polymers by standard wet spinning methods, i.e. extrusion of solvent solution of the polymer into a coagulation bath'containing an aqueous solvent mixture followed by extraction of the solvent from the fiber. It is'essential in the preparation of these fibers that stretching of the fiber after solvent removal be avoided so that the fiber be substantially unoriented as shown by X-ray diffraction patterns. It is, however, permissible for the fibers to be drawn in the spinning bath or extraction bath up to about 400 percent in length prior to. solventjremoval providing the fibers remain substantially unoriented. The initial coagulating bath should be maintained at a temperature between C. and 75 C. and containing up to about 70 percent of the spinning solvent, the solvent concentration varying inversely with Thereafter fibers are passed through aqueous bathshaving little or no solvent at temperatures between 40 C. and 100 C. The remaining solvent is subsequently removed from the fibers, "preferably in a drying oven at a temperature below 150 C; Thus by maintaining control over the rate of solvent removal from the fiber and by avoiding'substantially all stretching or orientation operationsafter solvent removal, we can achieve the particular nodular effect onthe surface of the fiber.

It is permissible and entirely possible by spinning techniques to achieve any desired shape offiber, i.e. either ribbon, round, or dog-bone in "cross section; Fibers rangmg in size between about 3 and 27 denier can be em- Q ployed in the pile structure of these fabrics, with particularly good results being'achieved with fibers ranging in size between 12 and 18 denier.

-Th e polymeric resin fibers which have been found useful in these novel pile fabrics are acrylonitrile polymers, particularly. the copolymers and terpolymers containing a substantial amount of acrylonitrile, preferably about 40 percent or more Other polymerizable compositions, par: ticularly one or more vinyl compositions such as vinyl acetate, vinyl chloride, vinylidene chloride, acrylamide, and the like, can be employed withthe acrylonitrile in preparing the copolymeric and terpolymeric resins. Particularly desirable results are achieved with a copolymer of acrylonitrile'and vinyl chloride containing about 40 percent acrylonitrile and about 60 percent vinyl chloride. We have found the size of the nodes on thersurface of the acrylonitrile fiber employed in the pile fabrics to be critical. Fibers havirigl node sizes less'than 2 microns and greater than 30 microns do not possess efficient soil hiding powers, and will not give the desirable effects as do the fibers having the node sizes between 2 microns and 30 microns. Particularly desirable results are'se; cured .with fibers having anode size ranging between about 4 and 16 microns,

ular surface. The opaque surface reflects more light in a diffused pattern than the transparent, smooth surface and adds to the overall lightness. Thus to the eye, a given black object, which in the case of soiling is dirt, may make fibers on the pile fabric either black or gray, depending upon the fiber surface geometry and background color. It is believed that this is the feature that is directly or indirectly responsible for the improved soil hiding power of these pile fibers.

This theory has been supported in our experiments using radioactive soil as the testing means. For example, carpets made from the nodular surfaced fibers could be loaded-up with a greater amount of dirt and still visually appear cleaner than eitherwool fibers or similar fibers having smooth surfaces free of any surface configurationsv The particular nodular surface of these fibers is readily visible under magnification such as by a 60-150 power binocular microscope using reflected light. Photographs of such fibers, when taken under reflected light and en'- larged to 500 times show the surface elevations as white dots which can be counted and estimated for size.

In addition to having a nodular surface, the fibers employed in the pile fabrics of this invention are further characterized as having a high degree of opacity. It is necessary that the fibers have both thesubstantially nodular surface and a high opacity factor to have good soil hiding power, neither of these elements alone being sufiicient to produce the desired soil-obscuring properties. We prefer to measure the opacity of the fibers, characterizing them by degrees of Opacity Factor.

By the term Opacity Factor we mean the optical density of a 4 mm, thick layer of the fiber to red light (70-0 millimicrons) when the fiber is immersed in a liquid having the same refractive index as the fiber. This measurement is made according to the following procedure. Fibers are prepared for Opacity Factor determination by scouring and boiling the fibers in. water for 30 minutes, thereafter drying the fibers at 60" C;, and re- Without desiring to be boundby any-particular it is our belief that the. soil hiding properties; of these lustering atl20 C. for 20 minutes.

Fiber samples in either yarn or tow form are wound evenly around an open rectangular support measuring i x /2" long under sufiicient tcnsionto keep the fibentaut so that each lap places twothicknesses of fiber in the form of yarnor tow in the light path. A

sufficient number of layers are wrapped on the support in a'uniform layer or film' so that no direct rays. of light can pass; The fiber carrying support is then immersed in a liquid having the same refractive index as the fiber (for example, acetophenonemay be used with vinyl chloride-acrylonitrile polymers having nearly thesarne index as the fiber) in a /2" x /2 X 1% rectangular light absorption cell having inside. dimensions. of X %"I The-occluded air bubbles are then removed from the cell by application of vacuum, generally about 25 inches Hg'being suflicieut to remove all entrapped air in about 40 minutes. r

The optical density is, then determined at the 700 millimicron. wave length light on a Beckman Model B Spectrophotometer, using the pure optical liquid as the standard for percent transmission. Opticalldensity is then determinedfdirectly from the calibratedf'scale' of 4.60,000 DP Opacity Factor mud wherein D represents the optical density of the fiber on the support immersed in the optical liquid, P represents the density of the fiber in grams per cubic centimeter, n represents the number of layers of yarn strands. wrapped on the samples holder, w represents the number of yarn strands per inch per layeron the sample holder, and d represents the denier of the yarn. The formula adjusts the observed value of the particular thickness of fiber layer used to that of a 4 mm. thick layer.

The fibers which We consider as having a high degree of opacity are those having an Opacity Factor determined in the above manner of at least 17. Opacity Factors in the range of 19 to about 25 or more are preferred. 1 It is commonly experienced in the spinning of these fibers that the nodular surface and high opacity are obtained together. It is preferred, however, that an opacifying agent such as titanium dioxide, antimony oxide, zinc oxide, or aluminum oxide be incorporated into the polymer to insure a high degree of opacity.

A preferred distinguishing feature of the new fibers directly related to the fiber surface is a high level of light diffusion compared to that of the conventional high soiling synthetic fibers having similar chemical and physical form and similar color and opacity but having smooth surfaces. This high diffusing power is indicated by a low Luster Index and may range invalue from about 1.15 to 1.85.

By the term Luster Index as employed herein, we mean a value calculated for the luster of the fiber as determined from the formula:

100 CRX NDF wherein CR is contrast reflectance as measured by a Hunter Multipurpose Reflectometer according to the general procedure described by R. S. Hunter, Journal of Research of the National Bureau of Standards, November 25, 1940, pp. 581-613, and NDF is either 1.0, or a constant factor of a Neutral Density Filter being one designated as 0.5 or 0.1 corresponding to NDF factors of 0.495 or 0.086 respectively as described by Hunter. The lower the value of the Lusterlndex of the fiber, the higher the diffusing power of the test surface. This high difiusing power of the fibers is presumably attributable to the many reflecting surfaces of the nodular surface. However, in other factors, such as dyeability and processability, the nodular surface fibers are at, least as good as smooth surfaced fibers produced by conventional means.

As would be expected from the use of a substantially Luster Index-- unoriented fiber, these nodular surfaced fibershave low tenacities, that is, between about 0.75 gram and 1.5. grams per denier as compared to about 2.5 grams per denier and above for the oriented fiber. While such weaker fibers would be disadvantageous in other fabrics we have discovered that their use in the pile component of pile fabrics actually serves to increase the wearing qualities of pile fabrics and also provides other results which are highly advantageous. Such fibers have little or no tendency to fibrillate or split on the ends. Thus no opportunity exists to hold dirt within the fibrillations, or to that and tuft together. This feature, we believe, serves further to extend the life of pile fabrics made, of such fibers. Thisproperty also makes it possible to cut the fibers cleaner, a factor of importance in carpet manufacture to secure a neater appearance on carpets,

fleeces, and simulated furs. Another factor of economic importance in the production of ,these' fibers is the elimination of the stretching and orientation step which reduces the costcof production.

, Another result achieved by the nodular-surface fibers is that of extending the wearability and service life of pile fabrics by reducing the tendency of fibers to slip in pile fabrics and thus eventually be worked loose and lost. This characteristic is apparently due to the enmeshing of the fiber surfaces which tend to reduce filament slippage. i

We have further found that the crush resistance of our pile fabrics, particularly in carpeting, is improved over that of the smooth surfaced fibersv Carpets made of the new fiber in the preferred ranges herebefore set forth have a crush resistance better than a comparable wool carpet and at least equal to the crush resistance of nylon.

The raised pile fabrics of this invention should have acrylonitrile polymeric resin fiber in the pile component of the fabric in order to possess the desirable features. The pile component can be composed of substantially all of the nodular surfaced fibers, or if desired, can be a blend of the nodular surfaced fibers with another synthetic resin or natural fiber.

While these nodular surfaced fibers have been found to be advantageously employed as the pile component in pile fabrics in general, particularly good results are obtained with pile carpeting. Of all types of pile fabrics, carpeting is subjected to the greatest abuse as far as wear and soiling is concerned. Thus the advantages shown for the nodular surfaced fibers show up to a greater effect in pile carpeting. It is not critical that the pile carpeting be produced in any particular manner. The carpeting can be either woven in round Wire or cut pile form, or tufted in loop or cut-pile form having a pile. structure composed of these nodular surfaced fibers. If desired, the carpetcan be back-sized with a rubber or resin latex or other commonly employed sizing material.

Standard cleaning methods, both vacuum and Wet and dry methods, are equally applicable to pile fabrics of this invention as they are to conventional pile fabrics. Likewise, dyeing techniques and yarn formation are not affected by the nodular surface on these fibers.

. In order to more objectively determine soil obscuring properties other than by visual means, we have adopted 'a test procedure called Soiling Additional Density as set forth by Rees, Journal of Textile Institute, 45, October 1954, pp. 612-617.. In determining the Soiling Additional Density of the carpeting, a standard dirt was formulated of 40 percent by Weight of bone charcoal, 40 percent carbon black, and 20 percent coal ash,- each ingredient being passed through a 200 mesh sieve'before blending. Squares of the carpeting, five inches on a side, and free of all finishes were rate-d for initial re-. flectance using a Hunter Multipurpose Reflectometer with atristimulus green filter after conditioning the samples in an atmosphere at about F. and 60 percent relative humidity. The tristimulus filter together with the photocell and light source in the reflectometersimulates "the average response of the human eye to the light spectrum. The samples were then soiled in a standard manner, by placing a template having a 3 inch square cut from the center and sprinkling 0.225 gram of the standard dirt uniformly over the exposed area of the carpet within the template. Two such soiled specimens were placed side by sideand a man weighing about pounds placed the. ball of each foot on the soiled areas of the samples and Walked in place on the specimens, each foot bearing. his weight 25 times. The man then turned and repeated the walking procedure. The specimens were then systematically cleaned with a tank-type vacuum again rated for reflectance both visually and with the. Hunter Multipurpose Reflectometer. The Soiling Additional Density was then calculated according to the with a steel scale.

- rubberlatex.

formula S.A.D.=lo'g R /R where R is the reflectance of the cle an'unsoiled specimen and R is the reflectance of the soiled area of the soiled specimen. In this manner, soil-obscuring properties are quantitatively established, with an increase in Soiling Additional Density representing an increase in apparent soiling. Stated conversely, the less the Soiling Additional Density, the greater-the soil-hiding properties.

Determination of fibrillation tendency of the fibers was by use of a Stoll Quartermaster Universal Wear Tester subjecting a bundle of about 40,000 fibers to end abrasion for l0,000 strokes employing 1/0 emery paper as the abradent. The test was made with a two pound surface abrasion head weight. At the end of the abrasion cycle, the abraded end of the fiber bundle was examined under a 150 power binocular microscope. Rating was made on the amount of splitting on the ends of fibers as to tendency .or non-tendency to fibrillate.

The following examples are-illustrative.

Example 1 A 60 percent vinyl chloride-40 percent acrylonitrile copolymeric. resin was dissolved in acetone to a polymer solids content of 27.5 percent. This mixture was then extruded through a spinnerette having 5000 apertures, each 0.10 mm. in diameter into an aqueous bath containing 70 percent acetone, maintained at 15 C. The fiber. tow was extruded at a rate of 50 feet per minute through this bath and into a second bath containing 2 to 4 percent acetone in water and maintained at a temperature of 47 C. The fiber tow was passed through the second bath and through draw rolls at a rate of 50 feet per minute and into a third bath of water containing no acetone, maintained at a temperature of 70 C. The fibers were stretched 100 percent in this third bath, dried, and relaxed at a maximum temperature of 105 C.

Individual fibers were 12 denier in size and had an Opacity Factor greater than 25, a Luster Index of 1.44,

.and a completely nodular surface with anode size ran ing from 4 to 11 microns. The fibers also had a tenacity of 0.85 gram per denier, ultimate elongation of 108 percent, and a shrinkage in boiling water of 2.7 percent. Fibrillation tests on the Stoll Wear Tester indicated the fibers had a high resistance to fibrillation. The fibers were substantially unoriented as shown by X-ray diffraction patterns.

The fibers were spun'in a one run, two ply woolen type yarn which was formed into a tufted carpet on a Ten-Tex rug tufting machine. The carpet had a row count of 5 and a pitch count of 11 measured according to the ASTM Standard Methods of Testing Pile Floor Coverings. (See ASTM Designation D-418-42 on page 559 of the ASTM Standards 'on Textile Materials published October 1954 by the American Society for Testing Materials, 'Philadelphia, Pennsylvania.) The length of the pile of the nodular surfaced fibers was 5/16 inch and was measured The carpet was backsized with a The carpet was soiled and cleaned also in the previously described manner and measured for change in color due to retained soil. The carpeting had a Soiling Additional Density of 0.69. 7

A carpet for control purposes was made in the same manner as the tested carpet, of 12 denier fibers having a smooth round cross section, free of surface nodes. The fibers for the control carpet. were made as described in Example 2. After'drying, the fibers had a cylindrical surface free ofv the nodular surface effect as viewed under a 60x binocular microscope. The fibers had an Opacity Factor of 16, a Tenacity of 1.9 grams per denier, an elongation of 52 percent, a shrinkage of 4.0 percent in boiling water, and a good resistance to fibrillation.

After soiling and cleaningas in the manner of the nodular surfaced fiber pile carpet sample, the control j carpet had afsoilingAdditional Density of 0392. This corresponds to an increase in apparent soiling of the smooth surfaced fibers of 33.3 percent compared to the nodular surfaced fiber carpeting of this invention.

Examp le 2 A 60 percent vinyl chloride-40 percent acrylonitn'le copolymeric resin was dissolved in acetone to a polymer solids content of 27.5 percent by weight. This mixture was extruded through a spinnerette having 2500 apertures, each 0.14 mm. in diameter, into a water bath containing 4.0 percent acetone, maintained at a temperature of 45 C. The fiber tow was extruded at a rate of 25 feet per minute and passed through submerged draw rolls in this bath at a rate of 48 feet per minute. The fiber tow was then passed to a water bath containing no acetone and maintained at 70 C. The fibers were drawn at a speed of 96 feet per minute in this bath, were dried, and relaxed at a maximum temperature of C. The fibers remained substantially unoriented as shown by X-ray diffraction patterns;

Individual fibers were of 12 denier size, had a ribbonlike cross section, an Opacity Factor greater than 25, Luster Index of 1.85, and a completely nodular surface with nodes ranging from size 3.6 microns to 15 microns. Fibrillation tests of a bundle of these fibers on a Stoll Wear Tester indicated the fibers had a high resistance to fibrillation. The fibers had tenacity of 0.89 gram per denier, an ultimate elongation of 102 percent, and a shrinkage in boiling water of 1.9 percent. The fibers were formed into a simulated round-Wire carpet sample, employing a tow consisting of 2500 fibersand a pile height of about 7/ 16 inch, with four rows per inch of the nodular surfaced fiber tow in one direction and two looped tufts per inch of the tow' in the other direction as the pile component of the carpet. The method employed gave a good simulation of commercial carpeting in pile height,density, and appearance for testing purposes.

The carpet was soiled and cleaned in the previously described manner and measured for change in color due to retained soil. The carpeting had a Soiling Additional Density of 0.75. V

A carpet for control purposes was made in the same manner as the tested carpet of oriented fibers of 12 denier having a smooth ribbon-like cross section, free of the nodular surface effect as viewed under a 60 X binocular miscroscope. The fibers were of the same acrylonitrile vinyl chloride copolymer by the process as disclosed in the patent to Rugeley et al., U.S. Patent 2,420,565. The fibers were Well oriented as shown by -ray diffraction patterns.' characteristically, these smooth surfacedfibers had an Opacity Factor of about 10, a Luster Index of 12.8, a tenacity of 3.0 grams per denier, an ultimate elongation of 35 percent, and a shrinkage in boiling water of 3.0 percent. Fibrillation of a bundle of fibers in the Stoll Wear Tester showed a high degree of fibrillation.

After soiling and cleaning the control carpet in the Example 3 I A 60 percent vinyl chloride-40 percent acrylonitrile resin was dissolved in acetone to a polymer solids content of 27.5 percent by weight. This mixture was then ex truded through a spinnerette having 5000 apertures, each 0.10 mm. in diameter into an aqueous bath containing 70 percent actone, maintained" at 15 C. The fiber tow was extruded at a rate of 50 feet per minute through this bath and into a second bath containing 2-4-percent acetone in water and maintainedat a temperature of' 47 C. The fiber towwas passed through the second bath and through draw rolls at a rate of 50 feet per minute and into a third bath of water containing no acetone, maintained at a temperature of 70 C. The fibers were stretched 100 percent in this third bath, dried, and relaxed at a maximum temperature of 105 C.

. Individually fibers were of 12 denier in size and had an Opacity Factor greater than 25, a Luster Index of 1.44, and a completely nodular surface with a node size ranging from 4 microns to 11 microns. The fibers also had a tenacity of 085 gram per denier, ultimate elongation of 108 percent, and a shrinkage in boiling water of 2.7 percent. Fibrillation tests on the Stoll Wear Tester indicated the fibers had a high resistance to fibrillation. The fibers were substantially unoriented as shown by X-ray diflraction patterns.

The fibers were formed into a simulated cut pile carpeting having these fibers in the pile structure. The carpet was soiled and cleaned also in the previously described manner and measured for change in color due to retained soil. The carpeting had a Soiling Additional Density of 0.99. I

.A carpet for control purposes was made in the same manner as the tested carpet of oriented fiber of 12 denier having a smooth ribbon shaped cross section free of surface nodes. The fibers were made as described in Example 2. After drying, the fibers had a smooth ribbon surface as viewed under a 60 X binocular microscope, free of any pebbly appearance. The fibers had a Opacity Factor of 10, a Luster Index of 5.0, a tenacity of 3.0 grams per denienamelongation of 35 percent, and a high tendency to fibrillate. The fiberswere well oriented as shown by X-ray diffraction patterns;

After soiling and cleaning as inthe manner of the nodular surfaced fiber sample, the controlcarp et had a S oiling Additional Density of 1.16. This corresponds to an increasein apparentsoiling of percent.

Example "4 I .A terpoly meric resin composed of 70 percent acrylonitrile, 20. percent vinyl. chloride, .and percent vinylidene chloride was dissolved in acetonitrile to a polymersolids content of 25 per cent by weight. This mixture was extruded through a spinnerette having 1250 holes each 0.14 mm. indiarneter into a water bath maintained at aftemperature of 60 C. The fiber tow wasxextruded ata rate of 30 feet perminute and passed through submerged draw rollsat a rate of 15 feet per. minute, and into a second water bathmaintained at170 C. at the same speed and then into a third water bath maintained at 95C. and through submerged draw rolls at a rate of 45 rest .per minute. The fiber was then dried and relaxed at a maximum temperature of 150 C. The fiber remained substantially unoriented as shown byX-ray diffraction patterns. p r A Individual fibers had adog-bone cross section approximately 25 denier in size,la tenacity .of 1.5. grams .per denier, .an ultimate elongation of 90. percent, no shrink- .agein boiling water, and a shrinkage in 300 F. dry heat of 0.3- percent, anOpacity Factor of 23, a Luster Index of 1.33 and acompletely nodular surface with a node size ranging in diameter from 2.4 microns to 10 microns. Fibrillation tests of a bundle ofthese fibers on a Stoll WearT-ester indicated the fibers had .no tendency to fibrillate. The fibers. in the form of tow were formed into a simulated cut wire carpet. consisting of four tufts perinch in one direction and four rows oftufts per inch in the other direction as 'the pile component; The

finished length of pile was inch. Thesimulated carpet was soiled and cleaned in the previously described maner and measured forchange -in color due toretained soil. he carpeting had a Soiling Additional Density 9130.98. 1 V3 f Acontrol carpet was made in thesame manner as the above sample using fibers of the same polymeric composi- ,tion also substantially, unoriented but free of the nodular surface-efliect. The fibers were made from the same -resin mixture described above which was extruded through a spinnerette having 1250 apertures each 0.14 mm. in diameter into a water bath containing 20 percent acetonitrile maintained at a temperature of 70 C. The fiber tow was extruded at a rate of 10 feet per minute and passed through submerged draw rolls at a rate of 15 feet per minute, and into a second and then into a third bath, each of which contained 10 percent acetonitrile at a temperature of 70 C. and finally through submerged draw rolls at a rate of 16 feet per minute. The fiber was then dried and relaxed at a maximum temperature of 140 C. This fiber was also substantially unoriented.

The fibers had a smooth dogbone-like cross section free of the nodular surface efiect as viewed under a 60 power binocular microscope. The fibers were approximately 16 denier in size, had a tenacity of 0.8 gram per denier, an ultimate elongation of 110 percent, no shrinkage in boiling water, and a shrinkage at 300 F. in dry 1 heat of 0.6 percent, an Opacity Factor of 12 and no tendency to fibrillate.

The control carpet after soiling and cleaning in the established manner had a Soiling Additional Density of 1.38, representing an increase in apparent soiling of over percent over the nodular surfaced fiber pile carpeting.

Example 5 A 60 percent vinyl chloride-40 percent acrylonitrile copolymer was dissolved in acetone to a. polymer solids content of 27.5 percent by weight. This mixture was extruded through a spinnerette having 2500 apertures each 0.14 mm. in diameter into a water bath containing 4.0 percent acetone, maintained at a temperature of C. The fiber tow was extruded at arate of 25 feet per minute and passed through submerged draw rolls in this bath at a, rate of 48 feet per minute. The fiber tow was then passed to a water bath containing no acetone and maintained at 70 C. The fibers were drawn at a speed of 96 feet per minute in this bath, were dried and relaxed at a maximum temperature of 105 C. The fiber remained substantially unorientedas shown by X-ray diffraction patterns.

Individual fibers were of 12 denier size, had a ribbonlike cross section, an Opacity Factor greater than 25, Luster Index of 1.85,..and a completely nodular surface with nodes ranging from size 3.6 microns to 15 microns. Fibrillation tests of a bundle of these fibers on a Stoll Wear Tester indicated the fibers had a high resistance to fibrillation. The fibers had a tenacity of 0.89 gram per denier, an ultimate elongation of 102 percent, and a shrinkage in boiling water of 1.9 percent.

The fibers were spun into a one run, two ply woolentype yarn which was formed into a simulated cut wire carpet consisting of 21 tufts per. inch in one direction and four rowsof tufts per inch in the other direction as the pile structure. The finished length of pile was 7 inch. The method employed. gave a good simulation of commercial carpeting in pile height, density, and appearance for testing purposes.

Thecarpet was soiled and cleaned in the previously described manner and measured for change in color due to retained soil. The carpeting had a Soiling Additional Density of 0.46.

carpet for control purposes was made in the same manner as the tested carpet of oriented fibers of 12 denier having ribbon-like cross section, and a surface free of the nodular surface effect as viewed under a 60 X binocular microscope. The fibers were made of the same acrylonitrile-vinyl chloride copolymer by the process as disclosed in the patent to Rugeley, et al. US. Patent 2,420,565. Opacity Factor of about 11, a Luster Index of 5.0, a

of QSZpercent, and a shrinkage in boiling water Of is These smooth surfaced fibers have an percent. Fibrillation of a bundle of fibers in the Stoll Wear Tester shows a high degree of fibrillation.

After soiling and cleaning in the manner as in the nodular surfaced fiber carpet as above, the control carpet had a'Soiling Additional Density of 0.71. This corresponds to an increase in apparent soiling of 54.4 percent over the nodular surfaced fiber pile carpeting of this invention.

Example 6' Cut-Wire carpeting was prepared from nodular surfaced fibers produced in the manner described in Example 2. The fibers had an Opacity Factor greater than 25, a Luster Index of 1.85, and a completely noded surface with a node size ranging in diameter from 3.6 microns to 15 microns and a high resistance to fibrillation, as determined on the Stoll Wear Tester.

A control carpeting wasprepared fromfibers produced in the manner. as described for the control sample of Example 2. The fibers'for the control carpet had an Opacity Factor of 1G, a Luster Index of 5.0, a tenacity of 2.5 grams per denier, an ultimate elongation of 50 percent, and a shrinkage in boiling water of 1.8 percent. The fibers had no discernible surface nodes and a high tendency to fibrillate.

The carpeting for the test and control samples was prepared from yarn on a woolen system, and made into cut-wire carpet with a row count of 7.3 rows per inch and a pitch count of 7.3 pile tufts per inch measured according to the ASTM Standard Methods of Testing Pile Floor Coverings. (ASTM Designation D-41842 on page 559 of the ASTM Standards on Textile Materials published October 1954, by the American Society for Testing Materials, Philadelphia, Pennsylvania.) The pile length was A inch measured with a steel rule.

As another control, an undyed wool carpetprepared in the same manner having a row count of 7.4 rows per inch, and a pitch count of 7.2 pile tufts per inch, and a pile length of inch, was employed.

Each of the above carpets was soiled and cleaned in the previously described manner of Example I, employing 225 milligrams the standard soiling compound containing 0L6 microcurie of radioactive phosphorus. After cleaning, the following measurements were made, using the wool carpet as thestandard for radioactivity index;

Visual "soiling Radio- Pile Fiber Appe'ar- Addiactivity ance tional Index Density Nodular Surface fiber. clean 0. 71 p 1. 36 Standard Smooth fibe 'dirty 1. 06 1. 22 Wool fiber 'dirty 1.05 1. GO

Thistest indicates that the new nodular surfaced'fiber carpet can be loaded up with a heavier amount of soil,

and ye't'appear cleaner than either wool carpet or the standard smooth fiber carpet;

Example 7 A copolymer of 90 percent acrylonitrileand 10 percent acrylarnide was dissolved in a mixture composed of' 85 percent ethylene carbonate and percent water to a solids content of 16 percent by weight. This mixture was extruded through a spinnerette having 100 holes each 0.10 mm. 'in diameter into a water bathmaintained at 12 of these fibers on a Stoll Wear Tester indicated the fibers had a low tendency to fibrillate.

Thefibers in the form of tow were formed into a simulated cut pile carpeting as the pile component, with five tufts per inch in one direction and four rowsperinch in the other direction. Each tuft contained 5500 filaments and was cut to a pile length of inch. The carpeting was soiled and tested as previously described and had a Soiling Additional Density of 0.68.

For a control fiber, a portion of the fiber spun under the above described conditions was not drawn under water but was extracted in water at C. for 20 minutes, stretched in steam 700 percent and relaxed 15 percent in 200 C. dry air. This procedure oriented .the fiber. The control fiber had a dogbone cross section approximately 2 denier in size, an Opacity Factor greater than 25, a surface free of the nodular surface effect as viewed under a 60 X binocular microscope and'a high tendency to fibrillate. The fibers in the form of tow were formed into a simulated cut pile carpeting as the pile component, with six tufts per inch in one direction and 4 rows per inch in the other direction. Each tuft contained 15,000 filaments and was cut to a pile length of 3 inch.

The carpeting was soiled'and tested as previously described and had a Soiling Additional Density of 0.96. This corresponds to an increase in apparent soiling'of over 40 percent over the nodular surfaced fiber pile carpeting. Example 8 Practical wear tests were made on round wire carpets made of wool and nylon'of carpet grade fibers (about 12 denier) and ona comparable round wire carpet having the pile structure composed of the nodular surfaced fiber in 12 denier, round filament form. The carpets were woven on a commercial-scale loom. This example illustrates that round wire carpeting produced on com,-

mercial-scale machinery from acrylonitrile polymeric fibers having nodular surfaces has resistance to soiling and retention of texture equivalent to or better than that of comparably produced wool carpeting, and far better than that of a comparably produced nylon carpeting. This example illustrates further than the crush resistance of the carpet made from the fibr having nodular surfaces is on a par with that of the carpet made from nylon, and is generally better than that of the carpet made from wool. I 1 r The nodular surfaced acrylonitrile polymeric fibers of this example were produced from a 60 percent vinyl chloride, 40 percent acrylonitrile resin which was dissolved in acetone and forced through a'spinnerette having'5000 apertures, each 0. 10 mm. in diameter, into an 0 aqueous ,bath containing 70 percent acetone, maintained at 15 The fiber tow then passed into asecond bath containing 5 to 8 percent acetone, maintained at 48 C.

Thefiber tow'then'passed between'draw rolls at theend of'the second bath, and then' into a third'bath containing 3 to 5 percent acetone, maintained at 70 C. The fiber tow was stretched percent in this third bath, then dried and relaxed at .a maximum temperature of C.

Individual fibers were of 12 denier size, had a round I cross section, an Opacity Factor greater than 25, a completely. nodular surface with nodes ranging in size from 3.4 micronsto 15.8 microns. The fibers had a' tenacity of 1.0 gram per denier, an ultimate elongation of percent, and a shrinkage in boiling water of 0.8 percent".

The fibers were substantially unoriented as shown by X-ray diffraction patterns. 7

These'fibers were spun into carpet yarns (1/1'14 carpet count) two ends of which were then plied. I These 'yarns, and comparable yarns of nylon and wool, were each woven on the same commercial-scale'loom into round wire carpeting of the Velvet type.' Spinning and weaving progressed routinely. The carpeting had a row count of' 8 and a pitch'co'unt of 8-measured according tothe ASTM Standard Methods of Testing Pile Floor Coverings. The length of the pile was inch and was meas ured with a steel scale. The carpet was backsized with a rubber latex.

. The individual carpets werecut to 18 inches by 27 inches and joined together along the 27 inch dimensions to form a multistrip carpet which was placed in a corridor with a high density of traffic five days a Week for eight weeks. The carpet was cleaned with a vacuum cleaner once a day, five days a week. Atthe ends of this time, visual and instrumental determinations of apparent soiling, change in texture, and crushing (loss in thickness) were made. The results from these determinations are tabulated as follows:

Apparent Soiling Crush Texture Resistance: Fiber Determined 1 oss of Deter- Visually Thickness,

mined S.A.D. percent Visually Wool; fair 0.14 Good 23.3 Nylon poor"-.- 0.24 Poor: marked 15.0

fuzzing and Y pilling. New, nodular surbest 0.13 Good 16. 3

faced fiber,12

denier, round fila-. ment.

Loss of thickness was measured with a Schiefer compressometer, employing a circular foot one inch in diameter and exerting a pressure of 1.0 pound per square inch, according to the method of:

Schiefer, Herbert F.: Wear Testing of Carpets, Re-

search Paper RP 1505, part of Journal of Research of the National Bureau of Standards, volume 29, November 1942, p. 347. 1

Measurements were made identically, both before and after the period of wear. The difference in thickness was divided by the initial thickness to provide the percentile loss in thickness.

- Example 9 Practical wear tests were made on cut-wire carpets made from the same fibers and in the same manner as described in Example 8. The same commercial-scale loom was employed in the weaving. The data are tabulated below:

What is claimed is:

1. A pile fabric having in the pile component a synthetic resin fiber, said synthetic resin being an acrylonitrile polymer having a substantial amount of acrylonitrile polymerized therein and said fiber being characterized by being substantially unoriented, having a high degree of opacity and a substantially nodular surface having nodes ranging in size between about 2 microns and 30 microns.

2. A pile fabric as in claim 1 wherein the acrylonitrile polymer is a copolymer containing a substantial amount of acrylonitrile and a different vinyl monomer polymerized therein.

3. A pile fabric as in claim 1 wherein the acrylonitrile polymer is a terpolymer containing a substantial amount of acrylonitrile and two different vinyl monomers polymerized therein.

4. A pile fabric having in the pile component a synthetic polymeric fiber of a vinyl polymer, one component of said polymer being acrylonitrile polymerized therein, said fiber characterized by being substantially unoriented, having a high degree of opacity and a substantially nodular surface having nodes ranging in size between about 2 microns and 30 microns.

5. A pile fabric havingin the pile component a synthetic polymeric fiber of a vinyl polymer containing acrylonitrile and vinyl chloride polymerized therein, said fiber characterized by being substantially unoriented, having a high degree of opacity and a substantially nodular surface having nodes ranging in size between about 2 microns and 30 microns.

6. A pile fabric in which the pile component is an acrylonitrile-vinyl chloride copolymer, said compolymer containing about 40 parts of acrylonitrile and about parts vinyl chloride by weight polymerized therein, said fiber characterized by being substantially unoriented, having a high degree of opacity and a substantially nodu lar surface having nodes ranging in size between about 2 microns and 30 microns.

7. A pile fabric in which the pile component contains a synthetic polymeric fiber of acrylonitrile-vinyl chloridevinylidene chloride terpolymer, said terpolymer containing about 70 parts of acrylonitrile; about 20 parts of vinyl chloride, and about 10 parts of vinylidene chloride by weight polymerized therein, said fiber characterized by being substantially unoriented, having a high degree of opacity and a substantially nodular surface having nodes ranging in size between about 2 microns and 30 microns.

8. A pile fabric in which the pile component contains a synthetic polymeric fiber of an acrylonitrile-acrylamide copolymer, said copolymer containing about 90 parts of crylonitrile and about 10 parts of acrylamide by weight polymerized therein, said fiber characterized by being substantially unoriented, having a high degree of opacity anda substantially nodular surface having nodes ranging in size between about 2 microns and 30 microns.

9. A pile fabric as in claim 1 in which the fiber is further characterized by having an Opacity Factor of at least 17 and a denier size between about 3 and 27 denier.

10. A pile fabric in which the pile component contains a synthetic fiber of a vinyl polymer containing acrylonitrile and vinyl chloride polymerized therein in which acrylonitrile is present in amounts of at least 40 percent j by weight, said fiber being characterized by being substantially unoriented, having an Opacity Factor of at least 17, a nodular surface having nodes ranging between about 4 microns and 16 microns, a denier size between about 12 and 18 denier, and a Luster Index between about 1.15 and 1.85.

11. A pile carpeting having as a pile component a synthetic resin fiber composed of a vinyl polymer, one component of said synthetic resin containing a substantial amount of acrylonitrile polymerized therein, said fiber characterized by being substantially unoriented, having a high degree of opacity and a substantially nodular surface having nodes ranging in size between about 2 microns and 30 microns.

12. A pile carpeting having as a pile component a synthetic resin fiber composed of a vinyl polymer containing acrylonitrile and vinyl chloride polymerized therein, in which the acrylonitrile is present in amounts of at least 40 percent by weight, said fiber characterized by being substantially unoriented, having a high degree of opacity and a substantially nodular surface having nodes ranging in size between about 2 microns and 30 microns.

13. A pile carpeting having a pile component comprising a synthetic fiber composed of a vinyl polymer containing acrylonitrile and vinyl chloride polymerized therein in which the acrylonitrile is present in amounts of at least 40 percent by weight, said fiber being characterized by being substantially unoriented, having an Opacity Factor of at least 17, a nodular surface having nodes ranging between about 2 microns and microns, anda denier size between about 3 and 27 denier.

l4. A pile carpeting having, in the pile component a synthetic resin fiber, said synthetic resin composed of a copolymer of acrylonitr'ile and vinyl chloride containing about 40 parts of acrylonitrile to about parts of vinyl chloride by weight polymerized therein, said fiber being characterized by being substantially unoriented, having a high degree of opacity, a nodular surface having nodes ranging between about 2 microns and 30 microns, and a denier size between about 3 and 27 denier.

15. A pile carpeting having a pile component comprising a synthetic resin fiber, said synthetic resin composed of a copolymer of acrylonitrile and vinyl chloride containing about 40 parts of acrylonitrile to about 60 parts of vinyl chloride by weight polymerized therein, and said fiber being characterized by being substantially unoriented, having an Opacity Factor of at least 17, a nodular surface having nodes ranging between about 2 microns and 30 microns", a denier size between about 3 and 27 denier, and a Luster Index between about 1.15 and 1.85.

16. A pile carpeting having a pile component comprising a synthetic resin fiber, said synthetic resin composed of a terpolymer containing about parts of acrylonitrile, about 20 parts of vinyl chloride, and about 10 parts of vinylidene chlorid e by weight polymerized therein, and

said fib'erfbeing characterized by being substantially vunoriented, having an Opacity Factor of at least 17, a nodular surface having nodes ranging between about 2 microns and 30 microns, a denier size between'about 3 and 27 denier. V a a 17; A pile carpeting having a pile component comprising a synthetic fiber composed of a copolymer of acrylonitrile and acrylamide containing about parts by weight of acrylonitrile and about 10 parts of acrylamide by weight polymerized therein, said fiber being characterized by being substantially unoriented, having an Opacity Factor of at least 17, a nodular surface having nodes ranging between about 2 microns and 30 microns, and a denier size between about 3 and 27.

References Cited .in the file of this patent UNITED STATES PATENTS 2,200,946 Bloch May 14, 1940 2,373,892 Hickey Apr. 17, 1945 2,374,744 Gregory May 1, 1945 2,416,390 Hifl. Feb. 25, 1947 2,736,946 Stanton et al. Mar.'6, 1956 UNITED STATES PATENT OFFICE CERTIFICATION OF CGRRECTION Patent Np. 2971 245 February 14 1961 'Theophilus A. rfijeild Jr, v et al0 It is h'ereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 5 lines 42 and 43, for "Bureau of Standards, November 25, 1940" read Bureau of Standarda 25 November 1940 column 8 line 47, for "misoroscope" read microscope column 9 I line 6 for -Ifudividual1y read my Individual column 1 line 35 for "crylonitrile" read acrylonitrile Signed and sealed this 22nd day of August 1961;

(SEAL) Attest:

ERNEST W. SWIDER DAVID L. LADD Attesting Officer Commissioner of Patents 

